crowley



March 10 1964 .1. E. CROWLEY ELECTRIC CONTROL APPARATUS Filed July 28,1961 INVENTOR. JOHN E. CRO LEY W ATTORNEY United States Patent 3,124,773ELECTRIC CGNTROL APPARATUS John E. Crowley, St. Anthony Viiiage, Minn.,assignor to Minneapolis-Honeywell Regulator Company, Minneapolis, Minn,a corporation of Delaware Filed July 28, 1961, Ser. No. 127,701 Claims.(Cl. 338-15ti) This invention relates to the field of electricalinstruments and more particularly to resistance elements for use in suchinstruments. A filar resistance member is incorporated in the edge of avery thin tape bearing meaningful indicia so that the resistance of themember from some measuring point is always coordinated with theassociated indicium. While such a concept is not new, there has beenheretofore no teaching of any practical way of accomplishing the desiredresult, that is, of physically securing a resistance member to the edgeof a thin flexible tape so that it remains fastened thereto during thenormal flexing of the tape in use, and so that continuous, reliablecontact with the resistance member along its entire length can readilybe assured.

An object of the invention is to develop a process for constructing aninstrument component comprising a flexible graduated indicator tape witha resistance member incorporated into one or both edges thereof forcontinuous engagement by an external electrical contact. Another objectof the invention is to provide a practical instrument component asdescribed above and a further object of the invention is to provide anew and improved laminated fabric for use in such electrical components.

Various other objects, advantages, and features of novelty notindividually enumerated above which characterize my invention arepointed out with particularity in the claims annexed hereto and forminga part hereof. However, for a better understanding of the invention, itsadvantages, and objects attained by its use, reference should be had tothe subjoined drawing, which forms a further part hereof, and to theaccompanying descriptive matter, in which I have illustrated anddescribed a preferred embodiment of my invention.

In the drawing, FIGURE 1 is a transverse cross sectional view of acompleted tape resistor according to the invention, FIGURE 2 is a crosssectional view of a step in the manufacture of the element, FIGURE 3 isa fragmentary side elevation of FIGURE 2, a portion being broken awayfor clarity of illustration, FIGURE 4 is an enlarged view of a portionof FIGURE 2, and FIGURE 5 is a view on a smaller scale of the apparatusof FIG- URES 2 and 3.

FIGURE 1 shows a laminated fabric including outer layers and 11 ofFiberglas and an intermediate layer 12 of nylon, with filar resistancemembers 13 and 14 partially embedded in the edges of the fabric foredgewise engagement by suitable external electrical contact means notshown. One or both of the outer surfaces of layers 10 and 11 may bearsuitable indicia, spaced linearly or nonlinearly, and the resistances ofmembers 13 and 14 are linear or nonlinear accordingly.

Each resistance element is constructed of a flexible core wire 15 onwhich is formed a helical winding 16 of resistance wire, insulated fromthe core and between the adjacent turns thereof, as shown in FIGURE 4.In one embodiment of the invention the core was 35 gage Formvarinsulated copper wire, and the resistance wire was .001 inch in diameterunder enamel insulation, and was of the alloy known as Oro G: obviouslyother suitable materials and dimensions may be used according to theneeds of the user.

The resistance element shown in FIGURE 1 is not easily constructed, andmuch effort was expended before a satisfactory method of making theseunits was invented.

In practicing this invention, a metallic disk 20 to act as a holdingfixture is first turned to provide a peripheral groove 21 somewhatdeeper and wider than the thickness and width of the tape andperipherally longer than the desired length of the tape. There is alsoprovided a pair of laminated fabric members 22 and 23 comprisingrespectively Fiberglas layers 24 and 25 and nylon layers 26 and 27. ATeflon cushioning strip 30 and a metal clamping'ring 31 are also used.

In making a resistance element, a tape 23 is placed in groove 21 withits Fiberglas surface against disk 20. An adhesive such as Cycleweld isapplied along one or both edges of the tape as at 32, and the resistancemember 13 is positioned next to the edge of groove 21. This is followedby another application of adhesive 33 and tape 22 is next applied withits nylon surface against the nylon surface of tape 23. Teflon strip 3this next applied and the whole assembly is fastened together by clampingring 31. Members 30 and 31 are slightly narrower than groove 21 so thatupon tightening ring 31, resistance members 13 and 14 are forcedoutwardly into engagements with the walls of groove 21.

The entire assembly is now heated to the point where the two abuttingnylon layers fuse into a single homogeneous layer in which theresistance elements are embedded except along the lines where theycontact the walls of groove 21. After a suitable curing interval, theclamping ring and cushioning strip are removed and the finished tape istaken from the disk and sugar-blasted along its edges to remove enameland foreign matter so that good electrical contact may be made with thewinding at any point along its length. The desired indicia may now beprinted on the tape surface and the element is ready for use.

In some cases it may be desirable to supply each of members 22 and 23with nylon strips on both sides of the Fiberglas, to act as an improvedbase for certain printing inks, and also to facilitate splicing of thecompleted device, if such is contemplated. Groove 21 may then be linedwith Teflon to prevent adhesion of the nylon to the disk.

Numerous objects and advantages of my invention have been set forth inthe foregoing description, together with details of the structure andfunction of the invention, and the novel features thereof are pointedout in the appended claims. The disclosure, however, is illustrativeonly, and I may make changes in detail, especially in matters of shape,size, and arrangement of parts, within the principle of the invention,to the full extent indicated by the broad general meaning of the termsin which the appended claims are expressed.

I claim as my invention:

1. In combination, a pair of coextensive elongated flexible members,each comprising at least a layer of Fiberglas and a layer of nylon,arranged with their nylon layers in contact, except along an edgethereof, to form a laminated fabric, an elongated filar resistanceelement partially between said members along said edge, and meansadhesively joining said element to said members.

2. The method of making a tape resistor from an elongated flexibleresistance element and a pair of laminated flexible tapes eachcomprising a surface layer of nylon, which comprises the steps of layingone of said tapes, nylon side out, in a groove, of substantially thesame width as the tape, in a heat transfer member, applying adhesivealong an edge of the tape, applying the resistance element to the edgeof the tape in contact with the adhesive so that it projects appreciablybeyond said edge, applying the other of said tapes nylon side down tothe first tape, applying pressure forcing the two tapes into intimatecontact, and heating the assembly to the point where the two nylonlayers amalgamate into a single mass.

3. The method of making a tape resistor, from a coiled, helicoid,flexible resistance element and a pair of laminated flexible tapes eachcomprising a surface layer of nylon, which comprises the steps of layingone of said tapes, nylon side out, in a groove, of substantially thesame Width as the tape in a heat transfer member, applying adhesivealong an edge of the tape, applying the V resistance element to the edgeof the tape in contact with the adhesive so that it projects appreciablybeyond said edge, applying the other of said tapes nylon side down tothe first tape, applying pressure forcing the two tapes into intimatecontact and heating the assembly to the point Where the two nylon layersamalgamate into a single mass.

- 4. A resistor comprising a lamina of a thermoplastic material such asnylon, an elongated resistance element substantially embedded in saidlamina along an edge there of so that a relatively small radial portionof said element extends beyond said lamina, and further laminae ofFiberglas overlying the first named lamina.

5. A resistor comprising a lamina of a thermoplastic material such asnylon, a coiled, helicoid resistance element substantially embedded insaid lamina along an edge thereof so that a relatively small radialportion of said element extends beyond said lamina, and further laminaeof Fiberglas overlying'the first named lamina.

References Cited in the file of this patent UNITED STATES PATENTS2,255,376 Bull et al. Sept. 9, 1941 2,427,979 Sorensen Sept. 23, 19472,617,011 MacKendrick Nov. 4, 1952 2,719,907 Combs Oct. 4, 19552,860,215 Williams Nov. 11, 1958'

1. IN COMBINATION, A PAIR OF COEXTENSIVE ELONGATED FLEXIBLE MEMBERS,EACH COMPRISING AT LEAST A LAYER OF FIBERGLAS AND A LAYER OF NYLON,ARRANGED WITH THEIR NYLON LAYERS IN CONTACT, EXCEPT ALONG AN EDGETHEREOF, TO FORM A LAMINATED FABRIC, AN ELONGATED FILAR RESISTANCEELEMENT PARTIALLY BETWEEN SAID MEMBERS ALONG SAID EDGE, AND MEANSADHESIVELY JOINING SAID ELEMENT TO SAID MEMBERS.